was the me 262 delay only hitler fault?

ThomasP said:

...
As for ".../aircraft models" I meant new variants of the 109 and 190. I possibly could have left that qualifier out of the discussion but I do not know how much it would take to fit a 2-stage DB engine into a 109,
...

Click to expand...

The Bf 109K-14 was supposed to used DB 605L. The 605L was slightly wider than 605D where supercharger was installed, otherwise it used same 'power section'.

Hey tomo pauk,

Thanks for the info on the 109K-14/605L combo. When you say the same power section, do you mean the same as the 'G' models or the same as earlier 'K' models (did the 'G' and 'K' use the same power section?). I am not familiar with the late-war 109 models, so any info would be appreciated, particularly any detail arrangement drawings.

ThomasP said:

Hey tomo pauk,

Thanks for the info on the 109K-14/605L combo. When you say the same power section, do you mean the same as the 'G' models or the same as earlier 'K' models (did the 'G' and 'K' use the same power section?). I am not familiar with the late-war 109 models, so any info would be appreciated, particularly any detail arrangement drawings.

Click to expand...

'Power section' is basically engine minus the supercharger section minus accessories (pumps mostly).
I don't have detail arrangement drawings, hopefully the new book by our member (Calum Douglas) will shed more light on this topic.

ThomasP said:

The Germans understood the theory and possible advantages of the Merlin 1&2-stage superchargers by late-1942. If they had started design/development for their engines, say in early-1943, it would have taken them until early-1944 to get a Merlinized-Hookerized 1- or 2-stage supercharger in service in any numbers.

Click to expand...

DB and Auto Union had used two stage superchargers on Formula I cars in 1939. The theory of a two stage supercharger being more efficient (less power needed and intake charge heated less for the same amount of boost) was well known and proved in practice.

Implementing two stage superchargers was a bit harder. Especially at the compression ratios aircraft superchargers had to use. The Mercedes Grand Prix engine used 2.31 Ata of boost at sea level (and was not using gasoline) so it was compressing the ambient air 2.31 times. An airplane that wants to use 1.42Ata at 26,000ft has to compress the ambient air 4 times.

In fighter aircraft especially trade-offs have to be made between weight and volume of a supercharger system and the increase efficiency or power of such a system.

Please remember that the Russians, French and Germans all played around with mounting a V-12 engine in the fuselage of a bomber to provide supercharged air to the engines in the wing for high flying bombers (makes turbos look simple).

What I mean by my statement "For the Germans, leaving out the fuel quality issue leaves engines that are pretty much equal to the US and UK engines in any operational sense, ..." is:

The DB 601/605 series filled the same niche as the Merlin for operational purposes when fitted to the 109 series airframe, and the BMW 801 and Jumo filled the same roll for the 190 series as the R-2800 or Allison. The engines may not have had the exact level of BMEP or boost that the Allied engines had but they still had enough performance to do the job.

Click to expand...

Unfortunately you can't leave the fuel situation out of it. The German engines were larger and heavier for the same power output as the Allied engines which puts them at a disadvantage in operations.

In theory 100/130 fuel will allow 50% more power than allied 91/96 octane fuel. Slot the German fuel in as you see see fit. In practice it didn't work quite that way and each engine was different but the advantage was large.







The US would have faced similar disruptions/delays (though probably not as severe) in production at a critical time for the Allied build-up/Lend-Lease. Would a Merlinized&Hookerized R-1820/R-1830/R-2600/R-2800/V-1710 in late-'43/early-'44 have made that much difference to the war effort? Would such engine/supercharger combinations have been worth the disruption in production?[/QUOTE]

Shortround6 said:

...
The German engines were larger and heavier for the same power output as the Allied engines which puts them at a disadvantage in operations.

Click to expand...

Larger and heavier by single digits percentage, or we're talking 20-30-more %?

probably single digits. A DB 605A is about 100lbs heavier dry than an Merlin XX series engine.
At certain altitudes the power difference is not great but at others (and once the 20 series is cleared for 14-16lbs boost) the power difference can be 150- 180HP? more for the Merlin.

With the number of Merlin's and the number of DB 600 series engines (and over 4--5 years) we can go back and forth on this but in general the Merlin was lighter.

Germans sometimes had to resort to the DB 603 engine to get the needed power (Me 410?) while the British still used a Merlin.

Shortround6 said:

probably single digits. A DB 605A is about 100lbs heavier dry than an Merlin XX series engine.
At certain altitudes the power difference is not great but at others (and once the 20 series is cleared for 14-16lbs boost) the power difference can be 150- 180HP? more for the Merlin.

Click to expand...

A de-rated DB 605A will make 100+ HP more at 18500 ft; fully-rated will add another 100 HP there. The 605AM (= 605A + MW 50) will make 200 HP more down low than Merlin 20 series at +18 psi.

With the number of Merlin's and the number of DB 600 series engines (and over 4--5 years) we can go back and forth on this but in general the Merlin was lighter.

Germans sometimes had to resort to the DB 603 engine to get the needed power (Me 410?) while the British still used a Merlin.

Click to expand...

Mosquito vs. Me 410 is comparing a knife with a stick, streamlining-wise.
2-stage Merlins, as installed, were probably heavier than DG 605AS/ASM/D engines, that went to ~740 kg dry, or 790-820 kg with accessories. The 2-stage V-1650 went to 800 kg with accessories, needing intercooler radiator and liquid.
Other Allied V12s were worse in power-to-weight or power-to-size or both.

"Mosquito vs. Me 410 is comparing a knife with a stick, streamlining-wise".

That's funny Tomo

parsifal said:

Once the resource equation had swung so decisively against Germany, and Germany was so demonstrably bleeding and wounded by Allied actions, the situation was dramatically changed. It made no sense to remain or elevate priority to projects that offered no prospect of immediate or short term benefit. You do not triage a critically wounded patient by going off and inventing some new gismo that might increase efficiency years down the track

Click to expand...

Completely agree, but therein lies the conundrum; the necessity of the situation requires haste, but that very same haste means bad decisions get made, or at the very least decisions on which outcomes that are not so well thought out are made. The problem with germany's wunderwaffen was that they were overly complex, the V2 for example, which required extraordinary manufacturing techniques and processes that the Germans were just not in a position to provide. They were being built in a cave by slave labour! Not only that, both the V 1 and V 2 programmes were not so much rushed, as development of the V 2 and rocketry in general by that team had been ongoing for years before 1943.

The V 1 was simple and existing technology married to an advanced concept and its operational debut was relatively easy to postpone, as it was done so in actuality through the destruction of launch sites on the French coast in anticipation of D-Day, resulting in a delayed first assault. Herein also lies the problem the Germans faced; their own priorities before the Allies are beginning to turn the tide. It made more sense for the German industrial machine to have developed a successful heavy four engined long range bomber from the outset than spend money on the likes of rockets - although this is seriously thinking in hindsight and would have required enormous foreight on the part of the Germans - something they obviously lacked. I remember reading in one of Speer's memoirs that the cost of a V 2 was about the same as building a B-17, but the B-17 could return and do the same job again, whereas the V 2 obviously couldn't.

The one thing in favor of the V-2, was it's ability to strike any target without warning and without any countermeasures.
It is truly fortunate for the Allies that the A4 (and related) program really never advanced beyond the point of where they were at by war's end.

Hey tomo pauk,

Thanks for the info. I thought you meant the engine, accessories, engine mounts, the part of the fuselage around the engine, etc. (i.e. the 'power egg' if it was built that way).


Hey Shortround6,

re: "Unfortunately you can't leave the fuel situation out of it. ... In theory 100/130 fuel will allow 50% more power than allied 91/96 octane fuel. Slot the German fuel in as you see see fit. In practice it didn't work quite that way and each engine was different but the advantage was large."

The reason I said "...leaving out the fuel quality issue..." is that although I have read in a few sources (some of them official intelligence reports) that at least some of the late-war German C3 fuel compared well to the Allied 130 grade, it does not appear that the German aircraft engines were ever built/able to use the full potential, at least not reliably in operations to any extent.

For example:

The DB 605 had a CR of 7.3/7.5 and was eventually cleared for (and reliable at) 1.42 ata. (+6.175 lbs) for a possible peak cylinder pressure of 156.5 lb/in^2.
The BMW 801D had a CR of 6.5 and was eventually cleared for (and reliable at) 1.42 ata. (+6.175 lbs) for a possible peak cylinder pressure of 135.7 lb/in^2.

As far as I am aware the only way either of the above engines was able to use higher boost was with some form of ADI.

Also, as far as I know the only German engine that saw large scale operational use that came close to comparable Allied engines in this respect is the DB 601N, which saw service in the 109 and 110 for a short period of about 1.5 years mid-war.

The DB 601N with a CR of 8.2 was eventually cleared for (and reliable at?) 1.53 ata. (+ 7.8 lbs) for a possible peak cylinder pressure of 184.4 lb/in^2

I do not know why the 601N compression ratio and boost were not carried over to the DB 605 series, but the only sane reason I can think of not to is that it proved to be unreliable (either due to the CR of 8.2 or due to the 1.53 ata., either or both in combination with the quality of the C3 fuel).

Some of the Allied engines (all of which saw large scale operational use) using 130 grade fuel for comparison, without ADI:

The Merlin XX series with a CR of 6.0 was eventually cleared for (and reliable at) +18 lbs (2.2 ata.) for a possible peak cylinder pressure of 196.2 lb/in^2.
The Hercules XVI with a CR of 7.0 was eventually cleared for (and reliable at) +8.25 lbs (1.56 ata.) for a possible peak cylinder pressure of 160.6 lb/in^2.

The V-1710-'E' series with a CR of 6.65 was eventually cleared for (and reliable at) 57"Hg (1.9 ata.) for a possible peak cylinder pressure of 185.6 lb/in^2.
The R-2800-'B' series with a CR of 6.75 was eventually cleared for (and reliable at) 53"Hg (1.77 ata.) for a possible peak cylinder pressure of 175.6 lb/in^2.

(My apologies to any Russian members - I am not familiar enough with their aircraft to use them for comparison also.)

ThomasP said:

...

The reason I said "...leaving out the fuel quality issue..." is that although I have read in a few sources (some of them official intelligence reports) that at least some of the late-war German C3 fuel compared well to the Allied 130 grade, it does not appear that the German aircraft engines were ever built/able to use the full potential, at least not reliably in operations to any extent.

For example:

The DB 605 had a CR of 7.3/7.5 and was eventually cleared for (and reliable at) 1.42 ata. (+6.175 lbs) for a possible peak cylinder pressure of 156.5 lb/in^2.
The BMW 801D had a CR of 6.5 and was eventually cleared for (and reliable at) 1.42 ata. (+6.175 lbs) for a possible peak cylinder pressure of 135.7 lb/in^2.

As far as I am aware the only way either of the above engines was able to use higher boost was with some form of ADI.

Also, as far as I know the only German engine that saw large scale operational use that came close to comparable Allied engines in this respect is the DB 601N, which saw service in the 109 and 110 for a short period of about 1.5 years mid-war.

The DB 601N with a CR of 8.2 was eventually cleared for (and reliable at?) 1.53 ata. (+ 7.8 lbs) for a possible peak cylinder pressure of 184.4 lb/in^2

Click to expand...

BMW 801D was cleared for 1.65 ata by late 1943 (this, for example, also this); CR 7.2 (it was 6.5 on 801A and C) . The DB 601N was good for 1.35 ata (power chart). BMW 801D was produced in much more examples than DB 601N and saw much greater use.
The DB 605D was cleared for 1.8 ata on C3 fuel, ditto for 605ASB and ASC engines.
Lager cylinders will not be easy to cool as it is the case with small cylinders thus one need to be careful with over-boosting (=advantage Merlin, V-1710) - the small-cylinder As 411 air-cooled V12 went to 1.8 ata at 3300 rpm with 87 oct fuel (CR 6.4).
High CR also limits the boost (= again advantage Merlin, then advantage V-1710).

I do not know why the 601N compression ratio and boost were not carried over to the DB 605 series, but the only sane reason I can think of not to is that it proved to be unreliable (either due to the CR of 8.2 or due to the 1.53 ata., either or both in combination with the quality of the C3 fuel).

Click to expand...

CR of 8.2 does not play well with 87 oct fuel, that DB 601E used. Germans probably shoot themselves in a foot with such high compression ratings - most of their mid-war engines were troublesome for 6-18 months after introduction (at least: DB 601N, 601E, 605A, BMW 801C and D, DB 603A).
The 605A was an evolution of 601E.

Some of the Allied engines (all of which saw large scale operational use) using 130 grade fuel for comparison, without ADI:

The Merlin XX series with a CR of 6.0 was eventually cleared for (and reliable at) +18 lbs (2.2 ata.) for a possible peak cylinder pressure of 196.2 lb/in^2.
The Hercules XVI with a CR of 7.0 was eventually cleared for (and reliable at) +8.25 lbs (1.56 ata.) for a possible peak cylinder pressure of 160.6 lb/in^2.

The V-1710-'E' series with a CR of 6.65 was eventually cleared for (and reliable at) 57"Hg (1.9 ata.) for a possible peak cylinder pressure of 185.6 lb/in^2.
The R-2800-'B' series with a CR of 6.75 was eventually cleared for (and reliable at) 53"Hg (1.77 ata.) for a possible peak cylinder pressure of 175.6 lb/in^2.

(My apologies to any Russian members - I am not familiar enough with their aircraft to use them for comparison also.)

Click to expand...

+18 psi = 2.3 ata?
The V-1710-63 (E series, meaning it has remote reduction gearbox) was cleared for 60 in Hg (a little above 2 ata?). There is a report by Ron Hazen where he confirms 60 in Hg for war emergency power for -39 and -73 engines (F series - 'classic' reduction gearbox, external spur type), while noting that engines were pushed to 66, and even to 70 in Hg in the war zones.
The AM-42 (for Il-10) was with CR of 5.5 (!) and 1565 mm Hg (= 61.6 in Hg; +15.5 psi). Other engines, like the VK-105PF or ASh-82FN went to 1200 mm Hg (47.2 in Hg, ~1.63 ata). Soviet fuel might not be as good as Allied 130 grade or late-war C3 fuel.

We are comparing fuels using two different scales of measurement.

The octane scale stops at 100. period.
The PN scale covers just about everything but due to custom is seldom used below 100. It was also only used during the war by the Americans and British.

There was a brief flirtation with trying to use 100 octane plus X CCs of lead but that was found to be very complicated and unworkable outside the lab.

The PN scale is pretty liner, the octane scale is not. depending on where you are on the scale the difference of 1 number on the octane scale can mean very little or it can mean a lot.

octane number........................PN number
70....................................................48.28
75....................................................52.83
80....................................................58.33
85....................................................65.12
87....................................................68.29
90....................................................73.68
91....................................................75.68
92....................................................77.78
95....................................................84.85
96....................................................87.50
97....................................................90.32
98....................................................93.33
99....................................................96.55
100.................................................100.0

There is a formula for a rough approximation of the manifold pressure that can be used when changing fuels, this is for illustrative purposes only. Explanation later.

since each engine is different you have to know what the maximum manifold pressure just short of knocking is. Example in the book is an engine running on 91/96 octane fuel will tolerate 36in of manifold pressure. you have to subtract 7in (a constant) and then figure the change in fuel. something like this going to 130 PN

[ (36-7) X 130/88 ] +7
(29 x 130/88) +7
42.8 +7= 50in Map.

now before anybody starts making spreadsheets or making any other claims, this ONLY applies if the fuel air ratio stays the same and the intake temperature stays the same.
Change any of the conditions in the intake and the answer is no longer even approximate.
Please note that engines using high levels of boost could see intake temperatures rise over 350 degrees F above ambient air so some method of intake charge cooling was almost mandatory regardless of the type of fuel used.

Even in 1950 91/96 grade fuel was about the highest grade that could be made with oil as it came from the ground. The Higher grades need extensive refining and chemical industry input.

The difference between 91/96 fuel and 100/130 fuel could be an increase of about 50% in power (this assumes the basic engine will tolerate that increase in power without self destructing).

ThomasP said:

The reason I said "...leaving out the fuel quality issue..." is that although I have read in a few sources (some of them official intelligence reports) that at least some of the late-war German C3 fuel compared well to the Allied 130 grade, it does not appear that the German aircraft engines were ever built/able to use the full potential, at least not reliably in operations to any extent.

Click to expand...

That is quite true but please remember that the allied engines were set up to use around 50% more fuel at high power settings than was needed for combustion/power. This extra rich mixture changed the detonation limits in the cylinder and acted like an internal coolant. R-2800s for example could go from in the mid to high 0.40lb fuel per hp hour when cruising to into the low 0.70s for take-off or combat power. The use of water injection actually cut the fuel usage by 0.75 gallons of fuel per minute on an F4U.
The Germans seemed to be focused on fuel economy rather than peak power (somewhat understandable given their fuel position) until late in the war.

Hey tomo pauk,

re: (this) and (this) for 1.65 ata.

I am pretty sure from reading the original, that this is referring to an ADI system using C3 instead of WM. I have read about this system before and my understanding is that it was never implemented to any extant due to the engine's inability to withstand the effects (or lack of effects?). I could be wrong about this as German is not my native language. The best I have ever seen for the 801 without ADI is 1.42 ata.


re: DB 605D/ASB/ASC at 1.8 ata.

All the 1.8 ata. values were with ADI (MW). Again, the best I have ever seen without ADI is 1.42 ata. for the 605, and 1.53 ata. for the 601N.


re: "+18 psi = 2.3 ata?"

14.7 + 18 = 32.7
32.7 / 14.7 = 2.2245 rounding to 2.2?

The 14.7 lb/in^2 was the normal value used by the UK in WWII for a standard atmosphere at sea level when talking about gauge boost pressures.


re: V-1710-E & _F series.

I have not been able to find any 'official' Specific Engine Flight Charts or Specific Engine Operation Charts that listed anything over 57" boost. I am not saying it did not occur, just that they were not 'officially' cleared.

Thanks for the other info. The Russian stuff is particularly helpful.

Hey Shortround6,

Something interesting I ran across a 1941 Federal Standards booklet a few years ago.

(begin quote)
The definitions below are the combined Army-Navy Aeronautical Specifications system as set out in 1940.

Spec. No. AN-VV-F-781 100 grade Sept 26, 1940 rev. June 6, 1941

Spec. No. AN-VV-F-776 91 grade Oct 15, 1940 rev. June 6, 1941

Spec. No. AN-VV-F-761 73 grade Oct 15, 1940 rev. June 6, 1941

Spec. No. AN-VV-F-761 65 grade Oct 15, 1940 rev. June 6, 1941

Type A Automotive 70 or 77 octane
Type B Automotive 70 or 77 octane
Type C Automotive 50 octane
(end quote)

Spec. No. AN-VV-F-776 prior to October 15, 1940 was USAAC 87 octane, aka USN 91 octane

There were several US standards for 100/xxx grade:
AN-VV-F-781 allowed upto 3 ml TEL/gal
AN-F-27-4 (AN-F-27 amendment 4) 2.5 ml TEL/gal = US 100/125 grade
AN-F-27-5 (AN-F-27 amendment 5) 3.0 ml TEL/gal = US 100/130 grade
AN-F-28-1 (AN-F-28 amendment 1) 3.0 ml TEL/gal = US & Uk 100/130 grade
AN-F-28-2 (AN-F-28 amendment 2) 4.6 ml TEL/gal = early US 115/145 grade
AN-F-33-0 (AN-F-33 amendment 0) 4.6 ml TEL/gal = 115/145 (AN-F-28-2 renamed to avoid confusion with 100/130 grade fuel)
AN-F-29-0 (AN-F-29 amendment 0) used xylidines & other aromatics to achieve 110/130 grade??
AN-F-44-0 (AN-F-44 amendment 0) 6.0 ml TEL/gal plus increased use of aromatics = US 150 grade which approximately equals UK 100/150 grade

Note that the the 100/130 grade varied in specific additives depending on whether it was US (TEL + alkylates) or UK (TEL + aromatics).

By 1939 the UK had standardized on upto 3.3 ml TEL/gal and a blend of aromatics (methylbenzine (aka toluene), dimethylbenzine (aka xylol), and ethylbenzene) to raise the basic 87 octane stock to 100 octane.

The US distilled/cracked most of its own aviation fuel and used a alkylate based process. When the US began supplying its 100 octane (US 100 octane) base stock in 1939 the UK found that the alkylate type did not meet its requirements for anti-knock and started blending it with aromatics and additional TEL to raise the lean/rich mixture to their current standard for 100 octane. The 'standard' for UK 100 octane changed as the war progressed until mid-1941 when they adopted the 100/130 grade used to the end of the war.

The USAAF standardized on 100/125 grade (AN-F-27-4) in early-1940 and this was the grade it entered the war with. The switch to 100/130 grade began in mid-1942 and was completed by late-1943. US specification AN-F-27-5 was the earlier AN-F-27-4 reblended with additional TEL and other additives to achieve the performance of 100/130 grade. US specification AN-F-28-1 was designed to meet the same minimum lean/rich mixture performance as the UK 100/130 grade, straight from the manufacturing plant, but using any of several different mixes of other additives plus TEL.

Hey Shortround6,

Also, thanks for the PN chart and the formula.

There may be a few missing standards (or amendments) from that list?

There were standards for 100/130 that allowed for first 4 ml TEL/gal and later 4.6 ml TEL/gal in order to increase production from roughly the same same amount of base stock. This also allowed for tens of thousands of tons less steel to be devoted to refinery construction.

The increase to 4 ml TEL/gal may have happened about Sept 1941 (Development Of Aviation fuels by S. D. Heron) but this may have been for 100 octane fuel before the standards for 100/130 were established. This step was supposed to have allowed an increase of 25% in production by decreasing the need for alkylate or other octanes.

Post war (1950?) there were two standards for 100/130 fuel, the commercial standard allowed for only 3 ml TEL/gal but the military standard allowed for 4.6 ml TEL/gal.

Fuel standards (and amendments) were coming pretty quickly in 1941/42/43 to suit the demand for better fuels while trying to accommodate vastly increased production while using the minimum of resources. This extended back into the steel requirements for increased refinery or chemical plant construction. One change was said to be worth enough steel for 15 destroyers which is an odd comment to make about aviation fuel production
But in 1942/43 with the battle of the Atlantic going on it makes a bit of sense.

ThomasP said:

Hey tomo pauk,

re: (this) and (this) for 1.65 ata.

I am pretty sure from reading the original, that this is referring to an ADI system using C3 instead of WM. I have read about this system before and my understanding is that it was never implemented to any extant due to the engine's inability to withstand the effects (or lack of effects?). I could be wrong about this as German is not my native language. The best I have ever seen for the 801 without ADI is 1.42 ata.

Click to expand...

The over-boosting via additional C3 injection was used in fighter-bomber versions of the Fw 190, but this is not it. There is a text in English (link) - scroll a bit - where the two systems of achieving over-boost are described (additional C3 injection, 'simple' over-boost).

re: DB 605D/ASB/ASC at 1.8 ata.

All the 1.8 ata. values were with ADI (MW). Again, the best I have ever seen without ADI is 1.42 ata. for the 605, and 1.53 ata. for the 601N.

Click to expand...

1.8 ata, for the DB 605Ds, were with just C3 fuel (roughly equivalent of Allied 100/130 grade by then), or B4 (87 oct)+ MW50. (data sheet1; data sheet2)
C3 + MW 50 werre supposed to give 1.98 ata. Conversely, the 2-stage 605L needed C3 fuel and MW 50 to attain 1.42 ata (no intercooler, high CR)!
1.42 ata was for the 605A on B4 fuel.
Erstwhile, the ASB and ASC engines were operating on C3 + ADI, and were re-rated for B4 + ADI, both for 1.8 ata.
Care to post the source for 601N making 1.53 ata?

re: V-1710-E & _F series.

I have not been able to find any 'official' Specific Engine Flight Charts or Specific Engine Operation Charts that listed anything over 57" boost. I am not saying it did not occur, just that they were not 'officially' cleared.

Click to expand...

Table from a manual:



V-1710 over-boosted: link

Hey Shortround6,

re: "There may be a few missing standards (or amendments) from that list?"

Yeah, I know. I have looked for more detailed/complete descriptions but so far I have only run across bits and pieces. Do you find that sort of thing as frustrating as I do?
I mean, you know that the information is out there somewhere, but where is it stored and how do we access it??

I have run across a few more specifications for pre-war and post-war grades, but not war-time.